Informed diagnostics proposes to demonstrate that cavity ring down spectroscopy (CRDS) instruments can measure 12CO2/13CO2 ratios with sensitivity comparable to mass spectroscopy in 13C-urea breath tests (UBT'S) for diagnosing infections by Helicobacter pylori. 13C-UBT's, with their inherent technical advantages and the cost reductions introduced by CRDS, will become the preferred H. pylori test for initial diagnosis as well as for follow-up tests to confirm a cure. Since the 13C-UBT with CRDS is a diagnostic method capable of offering results in real time, it will enable mass screening for H. pylori, a Class 1 carcinogen which infects 35 percent of Americans and two-thirds of the world's population. In Phase I, ID will demonstrate the feasibility of measuring gases in exhaled breath by CRDS. ID will design and build a prototype instrument with a novel system for sampling alveolar air, conduct preliminary accuracy testing with NIST-traceable standards, and establish the ability to detect changes in the concentration of 13CO2 ratios with adequate accuracy for the diagnosis of H. pylori infection. In Phase II, ID will develop a robust, user-friendly desktop instrument which technicians can operate at the point of care. ID will also conduct nationwide clinical trials. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE